Phonograph recording



Jan. 11, 19.44. GLASER ET AL 2,338,842

PHONOGRAPH RECORDING Filed May 28, 1941 Fig. 2

Patented J. ll, 1944:

PHONOGRAPH RECORDING Leo B. Glaler, Cranford, and Robert G. Franey,

Irvlngton, N. L,

aslignorl to General Instrument Corporation, Elizabeth, N. 1., acorporatlon of New Jersey Application May 28, 1941, Serial No. 395,528

' gagement of the turntable by the brushing devices .6Claims.

This invention relates to phonograph recording and particularly to thestripping or removing of the shavings or thread which are cut andsevered from the record by the cutting stylus in the recordingoperation.

The shavings or thread which are cut and severed from the record by thecutting stylus have been a constant source of trouble in professionaland home recording of phonograph records. These shavings, in the form ofan unbroken thread, are thrown off by the cutting stylus inwardly ontothe record surface. The unbroken thread (of substantial tensilestrength) as it is cut from the record deposits itself in cumulatingconcentric rings on the record surface and in doing so attaches itselfand tenaciously clings to the face of the record. It often occurs that asection of this thread works itself loose from the record surface andmigrates towards the cutting stylus and engages the same, with theresult that the thread exerts a pull sufficient to dislodge or move thecutting stylus and its arm from the record, thus causing an interruptionor break in the recording operation.

' To obviate this encountered difficulty, numerous suggestions have beenmade and many devices have been used, all designed to remove theshavings or thread from the seat of trouble. In professional recording,a suction device is used to suck up the thread immediately after it iscut, and blower devices have also been employed to blow the threadtowards the center of the record before it attaches itself to the recordsurface. In semi-professional and home recording, the thread is usuallybrushed towards the center of the record by the operator, various meansbeing employed for this purpose such as felt pads lightly impregnatedwith oil, metal fixtures lined on their bottoms with felt which rests onthe surface of the record during recording, brushes of light texture,or, as it is usually done, by a sweeping motion of the operators finger.Suction andv blower devices are, however, too expensive for homerecording purposes. Brushes and equivalent devices are usually onlysuccessful on very good recording blanks which have a highly polishedlow friction surface and are ineffective on recording blanks used inhome recording practice. Generally speaking, brush devices are diflicultto handle and to operate because the thread clinging to the recordsurface is dimcult to dislodge by brushing practice, and the use ofthese brushes requires constant attendance on the part of the operator.Furthermore, on recording machines with light power driving mechanisms,the enis apt to cause intermittent changes of speed of the turntable,resulting in the faulty reproduction known as wow."

In order to eliminate this encountered trouble in recording, records aresometimes made by the method of cutting from the inside out instead offrom the outside in. Since, due to the construction of the cuttingstylus, the shavings are thrown inwardly towards the center of therecord and, therefore, towards the already cut section thereof, thetrouble is thus largely, but not altogether, avoided if the record iscut from the inside out.

We have discovered that there is generated on or imparted to the threadin the cutting and severance thereof from the record an electrostaticcharge, and that it is due to this charge thereon that the threadattaches itself and tenaciously clings to the face of the recordresisting efforts to dislodge and remove the same. We have further foundthat by electrostatically charging a body or an element with a chargeopposite to that generated on or imparted to the thread in the cuttingoperation, and by positioning the thus electrostatically charged body orelement above the record, the cut thread is electrostatically attractedto the said charged body and thereby readily releases itself and isremoved from the record surface. With the use of such anelectrostatically charged element, the thread no longer winds itselfcumulatingly in concentric rings on the record surface but is removedtherefrom within a cycle of rotation of the record, the threaddepositing itself upon and wrapping itself about the charged element,from which it may then be readily stripped or removed. We haveIound'that sucn an electrostatically charged elemerit completely solvesthe problem, .thus obviating the use OI suction, blower or brushingdevices. The prime object of our present invention, therefore, relatesto the method of stripping the thread from the record based upon thesediscoveries, and to the device employed in practicing this method.

To the accomplishment of the foregoing and such other objects as mayhereinafter appear, the

. invention further consists in the method and device hereinafter soughtto be defined in the claims and described more in detail hereinbelow inconnection with the appended drawing, in which:

Fig. 1 is a, plan view of a phonograph recording apparatus of the homerecording type, showing the invention applied thereto; and

Fig. 2 is a view of the same with certain parts 2 removed, showing theelectrostatically charged body in operative and in displaced positions.

A conventional form of phonograph recording machine (of the homerecording type) is illustrated in the drawing. This machine may comprisea support ID, a turntable ll rotatably mounted thereon and operated byany suitable motive means (not shown) provided with a central metallicrecord receiving spindle l2, a reproducing unit l3 shown in itsinoperative position mounted on said support In, and a recording orcutting unit l4 also mounted on said support Ill and shown in anoperative position. As 11- lustrated in the drawing, the recording orcutting unit M, which may comprise any conventional cutter arm embodyinga, cutting stylus, is shown operating upon a record l5 which is movingin the direction indicated by the arrow IS, the record grooves alreadyout being indicated as IT.

As hereinbefore described, the shavings which are cut and severed fromthe record by the cutting stylus in producing the record grooves H, inthe form of an unbroken thread, are thrown off by the cutting stylusinwardly on to the record surface and the thread deposits itself incumulating concentric rings on the record surface as the record isrotated, and in doing so the thread attaches itself clingingly to theface of the record.

We have discovered as aforesaid that there is generated on or impartedto the thread in this cutting and severance thereof from the record, anelectrostatic charge and that it is due to this charge that the threadattaches itself to the face of the record resisting efforts to removethe same. We have found that this charge is a positive charge. and thatby electrostatically charging a body or an element with an oppositecharge, namely, with a negative charge, and by positioning the thusoppositely charged body above the record and at the recording areathereof, the cut thread is electrostatically attracted to the thuscharged body and thereby releases itself from the recording surface andis removed therefrom. I

This method of electrostatically stripping the thread from the recordmay be carried out in a variety of ways. We have found one, of thesimplest ways of accomplishing this is to provide a body which may beseparate from the phonegraph elements and which may be quickly moved tooperative or inoperative position. In its simplest form, such a body maycomprise a rod l8 preferably made of a suitable insulating material, onwhich a negative charge can be created, carried by or if desired madeintegral with a base support IS. The material of this electrostaticallycharged element may, for example, be rubber or resin, but we have foundthat a polished Styrene effectively yields the desired results. The rod18 and its base support l9 are so constructed that when the base ispositioned on the phonograph support III the rod I8 is positionedspacedly above the record (for example, about one-quarter of an inch)and extends inwardly in a general radial direction over a substantial.part of 'the recording surface. Preferably the rod I8 is of such alength that its inner end is positionable near the central metal spindlel2 for a purpose to be described. This positioning and arrangement ofthe electrostatically chargeable element is illustrated in the drawing,in Fig. 2 of which the element I8 is shown both in operative (full line)and in displaced (dot-and-dash line) positions.

When a recording is to be made, the rod element I8 is rubbed withacloth, such as an ordinary handkerchief, or held against the edge ofthe turntable and thereby becomes electrostatically charged. It is foundthat the charge created is sufficient to last for the, recording of acomplete record. So charged, it is placed in the position shown in Figs.1 and 2 of the drawing and the cutting or recording of the record isthen begun. As the record is cut, the shaving or thread indicated as 20(see Fig. 1) thrown inwardly by the cutting stylus no longer windsitself cumulatingly in concentric rings clinging to the record surface,but is removed therefrom within a single cycle of rotation of therecord, as shown in Fig. 1 of the drawing. As soon as this thread in therotation of the record approaches and passes under the charged rod l8,it is attracted thereto releasing itself from the record surface and thethread wraps itself about the rod H3 depositing itself completelythereon. As soon as a part of this thread now on the charged rod reachesthe central spindle l2 and becomes engaged thereby, the thread windsitself about the spindle 12 in the rotation of the latter, as shown inFig. l of the drawing, and in doing so is stripped or removed from therod I8. As the operation continues, both of these actions take place,namely, the attraction of the thread to and the wrapping of this threadabout the charged rod 18, and the stripping of the same from the rod bythe rotating spindle l2. The recording of the entire record may beaccomplished without any further attendance to the behavior of the outthread, since it is stripped or removed from the record as it isproduced.

This method may manifestly be carried out in a variety of ways. Insteadof providing a sep arate chargeable element and arranging the same asabove described, the chargeable element may obviously be attached as bymeans of a clip to the cutter arm, moving therewith over the recordingarea. While it is most convenient to mean insulating material for thechargeable element, it is apparent that metallic bodies may be usedsimilarly located or positioned as described, and that such metallicbodies could be continuously supplied with a charge by frictional meansoperated by the rotation of the turntable. The device illustrated in thedrawings, because of it simplicity and easy handling, is one of thepreferred means for carrying out the method of the invention.

The method of the present invention, the means employed therewith andthe results and advantages produced thereby will, in the main, be fullyapparent from the above detailed description thereof. By means of thismethod the shavings or thread are readily released and removed from therecord, completely solving the problem and thus eliminating the need ofsuction, blower or brush devices. We have found that brush contactingmeans such as is disclosed in our copending application Serial No.395,529, filed May 2.8, 1941, may also be employed in applying the newdiscoveries, but the method of the present invention is preferredbecause of the inductive action of the means employed, permitting thechargeable element to be spaced above the record without contacting thesame and thus without any possibility of marring the surface of therecord or affecting the speed of the turntable. The brush contactingmeans of our co-pending application is in essence an electrical brushmeans, and although it engages the record surface, does not act as abrush in the mechanical sense and does not materially mar the record orinterfere with the record operation.

It will be apparent that changes may be made in the carrying out of themethod and in the means employed therefor, without departing from theessence of the invention defined in the following claims.

We claim:

1. The method in phonograph recording of stripping the thread cut fromthe record by the cutting stylus which consists in electrostaticallycharging an element with a charge opposite to that imparted to thethread in the cutting and severance thereof from the record andpositioning the thus electrostatically charged element above the record,whereby the cut thread is attracted to said electrostatically chargedelement and removed from the face of the record.

2. The method in phonograph recording of stripping the thread cut fromthe record by the cutting stylus which consists in electrostaticallycharging a rod of insulating material with a charge opposite to thatimparted to the thread in the cutting and severance thereof from therecord, and positioning the said electrostatically charged rod over therecord and the recording area thereof, whereby the cut thread isattracted to and deposits itself upon said electrostatically chargedrod.

3. The method in phonograph recording of stripping the thread cut fromthe record by the cutting stylus which consists in electrostaticallycharging a rod with a charge opposite to that imp rted to the thread inthe cutting and severance thereof from the record, and positioning thesaid electrostatically charged rod above the record and staticallychargeable element being carried by f generally radially over therecording area thereof with the inner end of the rod near the centralmetal spindle of the phonograph turntable, whereby the cut thread isattracted to, deposits itself upon said electrostatically charged rodand is stripped therefrom by said central spindle.

4. A device for stripping the thread cut from the record by the cuttingstylus in phonograph recording comprising a support and an elementthereon electrostatically chargeable with a charge opposite to thatimparted to the thread in the cutting thereof from the record, the saidelectrothe support so as to be positionable abov the record and therecording area thereof during the recording operation.

5. A device for stripping the thread cut from the record by the cuttingstylus in phonograph recording comprising a supporting base and a rodthereon electrostatically chargeable with a charge opposite to thatimparted to the thread in the cutting thereof from the record, the saidrod being carried by the supporting base and extending therefrom so asto be positionable above the record and generall radially over therecording area thereof during the recording operation.

6. A device for stripping the thread cut from the record by the cuttingstylus in phonograph recording comprising a support and rod of aninsulating material electrostatically chargeable with a charge oppositeto that imparted to the thread in the cutting thereof from the record,

the rod being carried by the support and extending therefrom so as to bepositionable above the record and over the recording area thereof duringthe recording operation.

LEO B. GLASER. ROBERT G. FRANEY.

